Just how good are those used, sealed lead-acid batteries? [RE-wrenches]
Jeff Clearwater
clrwater at earthlink.net
Sat Oct 21 05:45:22 PDT 2006
<x-flowed>
Hey Bob,
Oh yes, of course. But the voltage and amperage curve will tell you
all you need.
Have fun!
jc
>Thanks, Jeff. Note, however, that, because these are sealed
>batteries, I will be unable to measure SG.
>
>Bob Clark
>SolarWind Energy Systems, LLC
>bclark at solar-wind.us<mailto:bclark at solar-wind.us>
> ----- Original Message -----
> From: Jeff Clearwater<mailto:clrwater at earthlink.net>
> To: RE-wrenches at topica.com<mailto:RE-wrenches at topica.com>
> Sent: Friday, October 20, 2006 8:59 PM
> Subject: Re: Just how good are those used, sealed lead-acid
>batteries? [RE-wrenches]
>
>
>
> HI Bob,
>
> Here's how you do it.
>
> First understand lead acid chemistry thoroughly by reading "Battery
> Book One" by Curtis instruments or some such book.
>
> Then do the following procedure.
>
> 1) Set up a charging station for each battery separately (not in any
> series and/or parallel arrangement).
>
> 2) Bring each battery to a good equalize charge state. For sealed
> lead acid you want a "constant current, constant voltage, constant
> current" type of 3 stage charge that is carefully regulated not to go
> past the 14.4 volt or whatever the battery manufacturer recommends
> for those batteries.
>
> 3) Set up a load station - use a resistance element like those used
> for dump loads. This should be on the order of a C/10 discharge
> rate. (i.e. if a 100 amphour battery - a 10 amp load)
>
> 4) Now here's the tricky part that requires attention and time.
> Discharge each battery with the load and note the start time and
> amperage and take careful voltage and amperage and specific gravity
> readings periodically - perhaps every 30 minutes or hour - record
> these readings in a spreadsheet like Excel or equivalent. Record the
> time and voltage and amperage and SG.
>
> 5) Discharge until the battery shows about 1.90-1.95 volts/cell at
> the C/10 rate. (11.4 - 11.7 volta for a 12 volt battery.
>
> 6) Graph the discharge curve you obtained - graph the voltage the
> amperage and the specific gravity on the same graph. Let the battery
> sit discharged for an hour or so and take SG and voltage readings
> again.
>
> 7) Now you can analyze this data quick and dirty or you can analyze
> it with sophisticated analysis. Quick and dirty is just to take the
> total time until you reached the state you reached times the amperage
> during that time (rough average) and that will give you rough
> amphours that the battery delivered to that theoretical state of
> charge. You can obtain State of Charge vs SG readings for your
> particular battery from the manufacturer. By comparing the
> theoretical new battery graph to yours you can roughly determine how
> much capacity yours has. This will also give you the relative health
> of each battery.
>
> A more sophisticated analysis might involve you integrating the area
> of the time vs amperage or time vs. SG curve and determining exact
> amphours. But you can tell alot if you just compare your curves to
> that of a new battery or the manufacturer's curves or even just to
> each other.
>
> Oh yea - then charge the batteries back up - don't let them sit discharged!
>
> You may have to do this procedure a few times - especially if the
> batteries have been sitting around - they may need "working" to get
> to accept a fuller charge.
>
> AND you need to assess whether all this labor is worth the price of
> these batteries! Most VRLA batteries don't last more than 200-300
> cycles max.
>
> Hope that helps!
>
> Best,
>
> Jeff Clearwater
> Village Power Design
>
>
> >Wrenches:
> >
> >I can quite easily measure the voltage of a sealed battery by using
> >a meter, but how do I know how "good" a used, sealed battery is?
> >That is, if the sealed, lead-acid battery has been in use for 2 to 3
> >years, how do I determine its condition (and capacity to hold a
> >charge) if I do not know its use history? I need to determine how
> >"good" each of 20 of these batteries are (I have reason to believe
> >that the condition of these batteries varies widely). I would hate
> >to have to haul them somewhere (except to recycle them if they are
> >no good) to be tested.
> >
> >Bob Clark
> >SolarWind Energy Systems, LLC
>
>>bclark at solar-wind.us<mailto:bclark at solar-wind.us<mailto:bclark at solar-wind.us>>
> >[Non-text portions of this message have been removed]
> >
> >
> >- - - -
> >To send a message: RE-wrenches at topica.com<mailto:RE-wrenches at topica.com>
> >
> >Archive of previous messages:
>http://lists.topica.com/lists/RE-wrenches/read<http://lists.topica.com/lists/RE-wrenches/read>
> >
> >List rules & how to change your email address:
> >www.mrsharkey.com/wrenches/etiquette.php
> >
> >Check out participant bios:
>www.mrsharkey.com/wrenches/<http://www.mrsharkey.com/wrenches/>
> >
> >Hosted by Home Power magazine
> >
> >Moderator: michael.welch at homepower.com<mailto:michael.welch at homepower.com>
>
>
> --
> ~~~~~~~~~~~~~
> Jeff Clearwater
> Village Power Design
> Sustainable Energy & Water Solutions for Home & Village
> http://www.villagepower.com<http://www.villagepower.com/>
> gosolar at villagepower.com<mailto:gosolar at villagepower.com>
> NABCEP (tm) Certified Solar PV Installer
>
> 530-470-9166
> 877-SOLARVillage
> 877-765-2784
> 65 Schoolhouse Rd
> Amherst, MA 01002
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~
>
>
> - - - -
> To send a message: RE-wrenches at topica.com<mailto:RE-wrenches at topica.com>
>
> Archive of previous messages:
>http://lists.topica.com/lists/RE-wrenches/read<http://lists.topica.com/lists/RE-wrenches/read>
>
> List rules & how to change your email address:
>www.mrsharkey.com/wrenches/etiquette.php<http://www.mrsharkey.com/wrenches/etiquette.php>
>
> Check out participant bios:
>www.mrsharkey.com/wrenches/<http://www.mrsharkey.com/wrenches/>
>
> Hosted by Home Power magazine
>
> Moderator: michael.welch at homepower.com<mailto:michael.welch at homepower.com>
>
>
>
>
>[Non-text portions of this message have been removed]
>
>
>- - - -
>To send a message: RE-wrenches at topica.com
>
>Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read
>
>List rules & how to change your email address:
>www.mrsharkey.com/wrenches/etiquette.php
>
>Check out participant bios: www.mrsharkey.com/wrenches/
>
>Hosted by Home Power magazine
>
>Moderator: michael.welch at homepower.com
--
~~~~~~~~~~~~~
Jeff Clearwater
Village Power Design
Sustainable Energy & Water Solutions for Home & Village
http://www.villagepower.com
gosolar at villagepower.com
NABCEP (tm) Certified Solar PV Installer
530-470-9166
877-SOLARVillage
877-765-2784
65 Schoolhouse Rd
Amherst, MA 01002
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~`~
- - - -
To send a message: RE-wrenches at topica.com
Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read
List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php
Check out participant bios: www.mrsharkey.com/wrenches/
Hosted by Home Power magazine
Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com
EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com
For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------
</x-flowed>
More information about the RE-wrenches
mailing list